The present invention relates to a silver-containing copper alloy coating to be applied to a surface of a bearing component, such as a bushing, and to a method of applying the coating to the bearing component.
Journal bearings are used as structural support for rotating parts. Important requirements for journal bearing materials include lubricity, high thermal conductivity, and fatigue strength. Common metallic journal bearing materials include alloys of tin, lead, aluminum, and copper. Of particular interest for the journal bearings in a fan drive gear system are copper alloys which contain 21% to 30% lead. The lubricity of these copper alloys derives from the presence of lead particles which are uniformly distributed in the copper matrix. Under adverse operating conditions, frictional heating has been shown to cause incipient melting and subsequent loss of the lead in the surface layer. Seizure of the bearings occurs rapidly when lead is depleted from the surface.
Accordingly, there remains a need for alloy materials which can be applied to bearing component surfaces and which have higher incipient melting temperatures than lead-containing copper alloys.
It is an object of the present invention to provide a copper alloy which can be advantageously used in bearing structures.
It is a further object of the present invention to provide a copper alloy as above which has a higher incipient melting temperature than lead-containing copper alloys.
It is yet a further object of the present invention to provide a copper alloy as above which exhibits lubricity and high thermal conductivity.
It is still a further object of the present invention to provide a method for applying the copper alloy of the present invention to a bearing surface in the form of a coating layer.
The foregoing objects are attained by the copper alloy and the method of the present invention.
In accordance with the present invention, a copper alloy is provided for use in bearing structures. The copper alloy comprises a binary copper alloy consisting of from about 15 wt % to 90 wt %, preferably from about 50 wt % to 60 wt %, silver and the balance essentially copper. The copper alloy is applied to a surface of a bearing component.
A method for forming a bearing structure is also disclosed. The method broadly comprises the steps of providing a bearing component and applying a layer of a copper base alloy consisting of from about 15 wt % to about 90 wt % silver and the balance essentially copper to a surface of the bearing component. The bearing component may be a bushing used in a journal bearing.